1. Field of the invention
The invention relates to a rotor for a rebound or impact crusher, comprising a number of discs disposed axially spaced out on a shaft, and beater blades which are disposed in marginal recesses in the discs and are each retained by an axially extending positive locking system provided between their rear side and the discs and on whose front sides directly by protective caps disposed on the discs.
2. Discussion of Prior Art
In a prior art rotor of the kind specified the beater blade is rigidly clamped between a supporting beam forming the rear-side locking system and the protective cap bearing directly against the beater blade on the front side. In that prior art rotor, therefore, the protective caps must not only retain the beater blades positively connected to the discs on the rear-side and protect the discs on the front side of the beater blade against the material to be crushed, but they must also support the beater blades when they are loaded by the material for crushing. In this prior art the beater blades are not secured axially (German OS 21 47 920).
In a different kind of prior art rotor the beater blades are also rigidly clamped in the discs, but not by directly bearing against the protective cap, but bearing against a clamping wedge clamped between the protective cap and the beater blade. It is true that in the last-mentioned prior art the beater blades are not supported directly on the protective caps, as in the previously-mentioned prior art, but are supported only indirectly via the clamping wedges; nevertheless, when the beater blades are loaded by the material for crushing, the protective caps must bear the forces acting on the beater blades (German Patent 24 12 508 B2).
In another prior art rotor the beater blades are positively retained by an axially extending spring-and-groove locking system on both the front and rear sides. The spring-and-groove locking system on both the rear and front sides consists of a rod which engages in the groove and extends over the whole rotor length. The front side rod is retained by protective plates screwed onto the discs. To secure them against axial displacement, the beater blades can be formed with recesses which are advantageously disposed on the rear side of the beater blade. Similarly to the other prior art rotor, in this case also the means disposed on the front side of the beater blade to fix the beater blade are loaded thereby when the lade is loaded by the material to be crushed (European Patent 0 209 757 A2).
Lastly, a rotor is known in which the beater blade engages positively on the rear side via a round rod engaging in a trough-shaped recesses and on the front side via an attachment formed on claming wedges of the protective cap and engaging in a trough-like recess in the beater blade. Due to this retaining system, when the rotor is stationary the beater blade is retained relatively loosely in the discs and is in practice merely secured against dropping out, while when the rotor rotates and centrifugal force is operative, the beater blade bears against the clamping wedge. In this rotor also, therefore, a part of the protective cap, mainly the clamping wedge, performs the function of bearing the loading of the beater blade by material for crushing (German Utility Model 79 11 613).